Buzzing on GSM audio (settings also work well with GTA01)

Eric Olson eric at
Sat Jul 26 18:20:48 CEST 2008

I'm just confirming that this helps audio on GTA01 as well.  Testing 
with another phone, I was able to get rid of echo almost entirely 
(between our two phones) by reducing Mono Playback Volume to 72. 
Hopefully, this will be loud enough to hear well in noisy places -- I'll 
have to try that out.
Here are the relevant numbers I settled on for now:
(Tmobile US, other side was a cell phone, indoors -- not a noisy area)

Mono Playback Volume 72
Speaker Playback Volume 118
Mic2 Capture Volume 3
Mono Sidetone Playback Volume 7
Bypass Playback Volume 7

On another note, the headset seemed to work well just now unless the 
headset mic was brought near the other phone or was touching the usb 
cable near the neo.  I didn't test it very long -- I'm sure there are 
other things that can cause interference.  At least I could hear some of 
the buzz on the neo side, so I can at least test it in everyday use and 
tell if there's interference (instead of entirely relying on the other 
person to tell me there's a problem like I did with echo).


Timo Jyrinki wrote:
> 2008/7/26 Andrew Bruno <aeb at>:
>> FWIW, I've found tweaking these specific settings in
>> /usr/share/openmoko/scenarios/gsmhandset.state effect the intensity of the
>> buzzing sound. Specifically:
>>  * 'Mono Playback Volume'   (85)
>>  * 'Mono Sidetone Playback Volume'  (7)
>>  * 'Mic2 Capture Volume'     (3)
> (buzz)
> ...
>>  * 'Speaker Playback Volume'  (112)
>>  * 'Bypass Playback Volume'    (7)
> (echo)
> Thanks! With these tweaks to my current settings, I've successfully
> for the first time received a confirmation that the receiver of my
> call didn't hear an echo of her own voice.
> However, I did tweak "Mono Sidetone Playback Volume" from 7 to 4,
> since in my own testings with two phones I heard quite a lot of buzz
> still. That lessened it, and the receiver seemed to hear my well
> enough anyway.
> My paranoid / not-knowing-what-I-do procedure is to:
> 1. change /usr/share/openmoko/scenarios/gsmhandset.state
> 2. alsactl -f /usr/share/openmoko/scenarios/gsmhandset.state restore
> 3. alsactl -f /etc/asound.state store
> 4. reboot
> I now added a link to your post at
> since this is the first time I really achieved some good results.
> -Timo
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